Die-casting system with enhanced adherence shot sleeve pour liner

ABSTRACT

A pour liner for a shot sleeve of a die-casting system including a bonding layer within a slot in a shot sleeve substrate and a refractory metal layer adjacent to the bonding layer. A method of manufacturing a shot sleeve including forming a slot in the slot sleeve, laser cladding a bonding layer within the slot, and laser cladding a refractory metal layer onto the bonding layer.

BACKGROUND

The present disclosure relates to die-casting and, more particularly, toan enhanced adherence slot sleeve pour liner for a shot sleeve.

In a die-cast tooling system, the plunger tip and the shot sleevecommonly encounter tool life limits. Shot sleeves typically encounterthree issues which may limit their continued use: thermal shock bymolten metal on the steel part at the pour area; warpage of the shotsleeve due to temperature differentials created inside the shot tube;and wear along the inner barrel of the shot sleeve whilst the pistonmoves.

Various methods have been attempted to increase shot sleeve life.Amongst these re-boring and installation of a larger diameter piston mayresolve wear. However, thermal shock at the pour area and warpage of theshot tube has not been effectively resolved and are only exacerbatedfrom high melting point alloys. Thus, die-casting has often been limitedto relatively low melting-point alloys to avoid thermal shock at thepour area and warpage of the shot sleeve that may otherwise contributeto jamming of the shot piston during operation.

Some die-cast tooling systems utilize a pre-fabricated pour insert of arefractory alloy welded into the shot sleeve body. The pour inserteffectively reduces the effect of thermal shock and facilitates rapidheat dissipation compared to typical tool steels. Since the pour insertis only welded into the tool steel, replacement is readily facilitated,however, the interface may not be sufficiently durable for continueddie-casting operations.

SUMMARY

A pour liner for a shot sleeve of a die-casting system according to onedisclosed non-limiting embodiment of the present disclosure can includea bonding layer within a slot in a shot sleeve substrate; and arefractory metal layer adjacent to the bonding layer.

A further embodiment of the present disclosure may include, wherein thepour liner is circular in cross section.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the pour liner is semi-circular incross-section.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the bonding layer and the refractorymetal layer are applied via a laser cladding process.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the bonding layer and the refractorymetal layer are applied layer-by-layer.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the bonding layer includes a nickelalloy.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the bonding layer is Inconel.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the refractory metal layer includes atantalum alloy.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the refractory metal layer includes atungsten alloy.

A die-casting system according to one disclosed non-limiting embodimentof the present disclosure can include a shot sleeve having a pour lineradjacent a pour hole, the pour liner including a bonding layer.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the bonding layer is adjacent to a shotsleeve substrate and a refractory metal layer is adjacent to the bondinglayer.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the pour liner is circular incross-section.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the pour liner is semi-circular incross-section.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the pour liner is flush with a cut inthe shot sleeve.

A method of manufacturing a shot sleeve according to one disclosednon-limiting embodiment of the present disclosure can include forming aslot in the slot sleeve; laser cladding a bonding layer within the slot;and laser cladding a refractory metal layer onto the bonding layer.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the bonding layer includes Inconel.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the refractory metal layer includes atantalum alloy.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein the refractory metal layer includes atungsten alloy.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include, wherein forming the slot includes forming theslot adjacent to a pour hole.

A further embodiment of any of the foregoing embodiments of the presentdisclosure may include comprising subjecting the bonding layer to a postweld heat treatment prior to laser cladding the laser cladding therefractory metal layer onto the bonding layer.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, the following descriptionand drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art fromthe following detailed description of the disclosed non-limitingembodiment. The drawings that accompany the detailed description can bebriefly described as follows:

FIG. 1 is a schematic cross-sectional view of a die casting mold;

FIG. 2 is a schematic longitudinal sectional view of a shot sleeve; and

FIG. 3 is a schematic lateral sectional view of the shot sleeveaccording to one disclosed non-limiting embodiment;

FIG. 4 is a schematic lateral sectional view of the shot sleeveaccording to another disclosed non-limiting embodiment; and

FIG. 5 is a method for the manufacture of a pour liner for a shot sleeveaccording to one disclosed non-limiting embodiment.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a die-casting system 10. The diecasting system 10 generally includes a reusable die 12 having aplurality of die elements 14, 16 that function to cast a component.Although two die elements 14, 16 are depicted, it should be appreciatedthat the die 12 could include more die elements, as well as other partsand configurations. The example die casting system 10 is illustrativeonly and could include more or less sections, parts and/or componentsincluding, but not limited to, horizontal, inclined, and vertical diecasting systems.

The die 12 is assembled and retained at a desired position via a clampmechanism 18. Such as a hydraulic, pneumatic, electromechanical and/orother configurations. The mechanism 18 also separates the die elements14, 16 subsequent to casting.

The die elements 14, 16 define internal surfaces that cooperate todefine a die cavity 20. A shot sleeve 24 is in fluid communication withthe die cavity 20 via one or more ports 26 located in the die element16, the die element 14, or both. A shot sleeve plunger 28 is receivedwithin the shot sleeve 24 and is moveable between a retracted andinjection position (arrow A) within the shot sleeve 24 by an actuator 30such as a hydraulic, pneumatic, electromechanical, or any combinationthereof.

The shot sleeve 24 is positioned to receive a molten metal from amelting unit 32, such as a crucible, for example. The melting unit 32operates to melt an ingot of metallic material to prepare a molten metalfor delivery to the shot sleeve 24, including but not limited to, vacuuminduction melting, electron beam melting and induction melting. Themolten metal is melted by the melting unit 32 at a location that isseparate from the shot sleeve 24 and the die 12.

Example molten metals for the die cast component include, but are notlimited to, nickel based super alloys, titanium alloys, high temperaturealuminum alloys, copper based alloys, iron alloys, molybdenum, tungsten,niobium, or other refractory metals. This disclosure is not limited tothe disclosed alloys, and it should be appreciated that any high meltingtemperature material may be utilized to die cast the component. As usedherein, the term “high melting temperature material” is intended toinclude materials having a melting temperature of about 1500° F. (815°C.) and higher.

The molten metal is transferred from the melting unit 32 to the shotsleeve 24 such as via pouring the molten metal into a pour hole 33 ofthe shot sleeve 24. A sufficient amount of molten metal is poured intothe shot sleeve 24 to fill the die cavity 20. The shot sleeve plunger 28is actuated to inject the molten metal under pressure from the shotsleeve 24 into the die cavity 20 to cast the component. Although thecasting of a single component is depicted, the die casting system 10could be configured to cast multiple components in a single shot.

Although not necessary, at least a portion of the die casting system 10may be positioned within a vacuum chamber. The vacuum chamber provides anon-reactive environment for the die casting system 10 that reducesreaction, contamination, or other conditions that could detrimentallyaffect the quality of the cast component, such as excess porosity of thedie cast component that can occur as a result of ingressed air duringmolten metal solidification.

With reference to FIG. 2, the shot sleeve 24 adjacent to the pour hole33 includes a pour liner 40 within a shot sleeve substrate 50. The pourliner 40 utilizes powdered refractory material deposited metallurgicallyand fused layer-by-layer into a slot 42 machined into an inner diameterof the shot sleeve substrate 50 axially located adjacent to the pourhole 33. In one embodiment, the slot 46 extends for about 180 degreesopposite the pour hole 33 (FIG. 3). In another embodiment, the slot 42extends for about 360 degrees at the axial location of the pour hole 33(FIG. 4).

The pour liner 40 is formed in a multi-layer manner in which a bondinglayer 44 such as Inconel e.g. IN625, is applied to the exposed toolsteel in the slot 42, then a refractory metal layer 46 such as tantalumor tungsten alloys is applied to the bonding layer 44. In one example,the bonding layer is about 3.8 mm thick and the refractory metal layeris about 0.2 mm thick. The bonding layer 44 provides a buffer againstdeleterious alloy diffusion from the highly alloyed base tool steelsubstrate into the refractory metal powder layer 46. The refractorymetal powder layer 46 is thereby provided with increased adherence.

With reference to FIG. 5, a method 100 to manufacture the shot sleeve 24initially includes machining the slot 42 (step 102). In one example, theslot 42 is either a semicircular (FIG. 3) or a circular (FIG. 4) slotthat extends for about six inches and is located adjacent to the pourhole 33.

Next, the bonding layer 44 is applied (step 104). In one embodiment, thebonding layer 44 may be applied via a laser cladding process in which anickel alloy powder, such as IN625 powder is communicated into the slot42 while interacting with an impinging laser beam. The laser melts thepowder and the melt is fused into the base metal substrate 50 of theshot sleeve 24. The powder is thereby solidified and built-uplayer-by-layer to a desired thickness leaving a final clad thicknessawaiting deposit.

The bonding layer 44 may then be subjected to a post weld heat treatment(step 106). The optional post weld heat treatment may be performed toreduce the thermal stress before the final refractory metal layer 46clad.

The refractory metal layer 46 is then applied (step 108). As with thebonding layer 44, the refractory metal layer 46 may be applied via alaser cladding process. In another embodiment, a separate nozzleconfiguration may be utilized to pre-place the refractory metal powdermixed with binder material.

The refractory metal layer 46 clad forms relatively fine grain sizes oftunable hardness by laser beam operation adjustments and the interplaybetween the power type power, feed rate, and/or time rasteringlayer-by-layer. Layer-by-layer, the refractory metal layer 46 may bebuilt up until proud of the slot 42. The bonding layer 44 provides arelatively stronger joint since the layers are metallurgical bondedlayer by layer and reduced crack susceptibility for improved adherencedue to the nickel buffering layer operating as a diffusion barrieragainst the highly alloyed tool steel.

Finally, the shot sleeve 24 may be machined such as by being honed tosize to yield the localized refractory metal clad area within the shotsleeve 24 (step 110).

The refractory metal lined shot sleeve provides enhanced tool life dueto reduced thermal fatigue cracks at the pour area. The refractory metallined shot sleeve 24 also avoids potential fluid/oil line leakage ascracks are reduced and wash-out effects at the pour area are avoided.The powdered laser clad process further permits tunable properties atthe pour area as well as repair.

The use of the terms “a,” “an,” “the,” and similar references in thecontext of description (especially in the context of the followingclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or specifically contradicted bycontext. The modifier “about” used in connection with a quantity isinclusive of the stated value and has the meaning dictated by thecontext (e.g., it includes the degree of error associated withmeasurement of the particular quantity). All ranges disclosed herein areinclusive of the endpoints, and the endpoints are independentlycombinable with each other. It should be appreciated that relativepositional terms such as “forward,” “aft,” “upper,” “lower,” “above,”“below,” and the like are with reference to the normal operationalattitude of the vehicle and should not be considered otherwise limiting.

Although the different non-limiting embodiments have specificillustrated components, the embodiments of this invention are notlimited to those particular combinations. It is possible to use some ofthe components or features from any of the non-limiting embodiments incombination with features or components from any of the othernon-limiting embodiments.

It should be appreciated that like reference numerals identifycorresponding or similar elements throughout the several drawings. Itshould also be appreciated that although a particular componentarrangement is disclosed in the illustrated embodiment, otherarrangements will benefit herefrom.

Although particular step sequences are shown, described, and claimed, itshould be understood that steps may be performed in any order, separatedor combined unless otherwise indicated and will still benefit from thepresent disclosure.

The foregoing description is exemplary rather than defined by thelimitations within. Various non-limiting embodiments are disclosedherein, however, one of ordinary skill in the art would recognize thatvarious modifications and variations in light of the above teachingswill fall within the scope of the appended claims. It is therefore to beappreciated that within the scope of the appended claims, the disclosuremay be practiced other than as specifically described. For that reasonthe appended claims should be studied to determine true scope andcontent.

What is claimed is:
 1. A pour liner for a shot sleeve of a die-castingsystem, comprising: a bonding layer within a slot in a shot sleevesubstrate; and a refractory metal layer adjacent to the bonding layer.2. The pour liner as recited in claim 1, wherein the pour liner iscircular in cross section.
 3. The pour liner as recited in claim 1,wherein the pour liner is semi-circular in cross-section.
 4. The pourliner as recited in claim 1, wherein the bonding layer and therefractory metal layer are applied via a laser cladding process.
 5. Thepour liner as recited in claim 4, wherein the bonding layer and therefractory metal layer are applied layer-by-layer.
 6. The pour liner asrecited in claim 1, wherein the bonding layer includes a nickel alloy.7. The pour liner as recited in claim 1, wherein the bonding layer isInconel.
 8. The pour liner as recited in claim 1, wherein the refractorymetal layer includes a tantalum alloy.
 9. The pour liner as recited inclaim 1, wherein the refractory metal layer includes a tungsten alloy.10. A die-casting system, comprising: a shot sleeve having a pour lineradjacent a pour hole, the pour liner including a bonding layer.
 11. Thesystem as recited in claim 10, wherein the bonding layer is adjacent toa shot sleeve substrate and a refractory metal layer is adjacent to thebonding layer.
 12. The system as recited in claim 10, wherein the pourliner is circular in cross-section.
 13. The system as recited in claim10, wherein the pour liner is semi-circular in cross-section.
 14. Thesystem as recited in claim 10, wherein the pour liner is flush with acut in the shot sleeve.
 15. A method of manufacturing a shot sleeve,comprising: forming a slot in the slot sleeve; laser cladding a bondinglayer within the slot; and laser cladding a refractory metal layer ontothe bonding layer.
 16. The method as recited in claim 15, wherein thebonding layer includes Inconel.
 17. The method as recited in claim 15,wherein the refractory metal layer includes a tantalum alloy.
 18. Themethod as recited in claim 15, wherein the refractory metal layerincludes a tungsten alloy.
 19. The method as recited in claim 15,wherein forming the slot includes forming the slot adjacent to a pourhole.
 20. The method as recited in claim 15, further comprisingsubjecting the boding layer to a post weld heat treatment prior to lasercladding the laser cladding the refractory metal layer onto the bondinglayer.